.. title: Building k3s on a Pi .. date: 2020-08-09 .. slug: building-k3s-on-a-pi .. updated: 2020-08-09 .. status: published .. tags: kubernetes, k3s, arm .. category: k3s .. authors: Elia el Lazkani .. description: I have decided to make a better use of my pi, k3s came next. .. type: text I have had a **Pi** laying around used for a simple task for a while now. A few days ago, I was browsing the web, learning more about privacy, when I stumbled upon `AdGuard Home `_. I have been using it as my internal DNS on top of the security and privacy layers I add to my machine. Its benefits can be argued but it is a DNS after all and I wanted to see what else it can do for me. Anyway, I digress. I searched to see if I could find a container for **AdGuard Home** and I did. At this point, I started thinking about what I could do to make the `Pi `_ more useful. That's when `k3s `_ came into the picture. .. TEASER_END Pre-requisites ============== As this is not a **Pi** tutorial, I am going to be assuming that you have a *Raspberry Pi* with **Raspberry Pi OS** *Buster* installed on it. The assumption does not mean you cannot install any other OS on the Pi and run this setup. It only means that I have tested this on *Buster* and that your milage will vary. Prepare the Pi ============== Now that you have *Buster* already installed, let's go ahead and `fix `_ a small default configuration issue with it. **K3s** uses ``iptables`` to route things around correctly. *Buster* uses ``nftables`` by default, let's switch it to ``iptables``. .. code:: text $ sudo iptables -F $ sudo update-alternatives --set iptables /usr/sbin/iptables-legacy $ sudo update-alternatives --set ip6tables /usr/sbin/ip6tables-legacy $ sudo reboot At this point, your *Pi* should reboot. Your **OS** is configured for the next step. Pre-install Configuration ========================= After testing **k3s** a few times, I found out that by *default* it will deploy a few extra services like `Traefik `_. Unfortunately, just like anything the *default* configuration is just that. It's plain and not very useful from the start. You will need to tweak it. This step could be done either *post* or *pre* deploy. Figuring out the *pre-deploy* is a bit more involving but a bit more fun as well. The first thing you need to know is that the normal behavior of **k3s** is to deploy anything found in ``/var/lib/rancher/k3s/server/manifests/``. So a good first step is, of course, to proceed with creating that. .. code:: text $ mkdir -p /var/lib/rancher/k3s/server/manifests/ The other thing to know is that **k3s** can deploy *Helm Charts*. It will create the *manifests* it will deploy by default, before beginning the setup, in the manifest path I mentioned. If you would like to see what it deployed and how, visit that path after **k3s** runs. I did, and I took their configuration of **Traefik** which I was unhappy with its *defaults*. My next step was securing the *defaults* as much as possible and I found out that **Traefik** can do `basic authentication `_. As a starting point, that's great. Let's create the credentials. .. code:: text $ htpasswd -c ./auth myUser That was easy so far. Let's turn up the notch and create the manifest for **k3s**. Create ``traefik.yaml`` in ``/var/lib/rancher/k3s/server/manifests/`` with the following content. .. code:: yaml --- apiVersion: helm.cattle.io/v1 kind: HelmChart metadata: name: traefik namespace: kube-system spec: chart: https://%{KUBERNETES_API}%/static/charts/traefik-1.81.0.tgz valuesContent: |- rbac: enabled: true ssl: enabled: true dashboard: enabled: true domain: traefik-ui.example.com auth: basic: myUser: $ars3$4A5tdstr$trSDDa4467Tsa54sTs. metrics: prometheus: enabled: false kubernetes: ingressEndpoint: useDefaultPublishedService: true image: "rancher/library-traefik" tolerations: - key: "CriticalAddonsOnly" operator: "Exists" - key: "node-role.kubernetes.io/master" operator: "Exists" effect: "NoSchedule" It's a **Pi**, I don't need prometheus so I disabled it. I also enabled the dashboard and added the credentials we created in the previous step. Now, the *Helm Chart* will deploy an ingress and expose the dashboard for you on the value of ``domain``. .. note:: I figured out the values to set in ``valuesContent`` by reading the *Helm Chart* K3s === If everything is in place, you are ready to proceed. You can install **k3s**, now, but before I get to that step, I will say a few things about **k3s**. **K3s** has a smaller feature set than **k8s**, hence the smaller footprint. Read the documentation to see if you need any of the missing features. The second thing to mention is that **k3s** is a one binary deploy that uses **containerd**. That's why we will use the script installation method as it adds the necessary **systemd** configuration for us. It is a nice gesture. Let's do that, shall we ? .. code:: text $ curl -sfL https://get.k3s.io | sh -s - --no-deploy traefik .. note:: We need to make sure that **k3s** does not deploy its own **traefik** but ours. Make sure to add ``--no-deploy traefik`` to our deployment command. Point ``traefik.example.com`` to your **Pi** ``IP`` in ``/etc/hosts`` on your machine. .. code:: text traefik.example.com 192.168.0.5 When the installation command is done, you should be able to visit `http://traefik.example.com/ `_ You can get the *kubeconfig* from the *Raspberry Pi*, you can find it in ``/etc/rancher/k3s/k3s.yaml``. You will need to change the ``server`` **IP**. Conclusion ========== If you've made it so far, you should have a **k3s** cluster running on a single *Raspberry Pi*. The next steps you might want to look into is disable the *metrics* server and use the resources for other things.